Aortic aneurysms are enlargements of the aorta that pose a health threat due to potential rupture. Minimally-invasive repair by endovascular stent grafts (endografts) has become a viable treatment option that avoids the risk of traditional open surgical repair. However, these endografts can only be used when the graft can be placed in a stable position without covering major branch vessels. This typically excludes patients with abdominal aortic aneurysms adjacent to the renal arteries (juxtarenal aneurysms) from endovascular treatment. To allow for endovascular repair of a wider range of aneurysm cases, surgeons will sometimes cut holes in the stent grafts to accommodate specific branch vessel origins, a process known as 'fenestration'. The openings are located based on CT images of the vessel origins. Longitudinal distances are measured, and relative angular locations are estimated from a reference point. However, these manual measurements take time and can lead to errors in the positions of the openings, particularly when multiple branches must be accommodated. To provide for faster and more accurate endograft fenestration, we propose the development of a custom template to serve as a guide for graft fenestration. We will use a patient's CT image data to generate a 3D rigid sleeve representing the segment of their aorta encompassing the branch vessels of interest. The sleeve will be produced with a 3D printer and it will include holes at the locations of the branch vessel origins. The sleeve can then be sterilized, slipped over the endograft, and rotated to avoid positioning the holes over stent strut. The openings can be cut with the sleeve in place, or their locations can be marked with a sterile pen and cut with the sleeve removed. Because the sleeve is generated from images of each patient's aorta, the template assures accurate angular and longitudinal placement of all fenestrations to match the aorta branch vessels. A fast and accurate custom fenestration method will save procedural costs and make minimally-invasive aneurysm repair procedures available to more patients.